Recirculating entrainment device for forced air heating systems



April 6, 1954 c. L. GRANDSTAFF 2,674,177 RECIRCULATING ENTRAINMENT DEVICE FOR FORCED AIR HEATING SYSTEMS Filed Aug. 4, 1951 I i I /IO M. I

i/ I l INVENTOR. 1 Clarence L. Grandsfaff Patented Apr. 6, 1954 Application. Augustj, 1951; seriamo. 240,426

' invention relates in forced warm *air heat-.- ing systems ofthe: type wherein atle'ast'one space to be heated thereby is'provided' with atleast one duct served atone end'withhotzair ata substan-' tial' pressure, as fromxa central furnace with blower, has adjacent its opposite end a warm airi outlet to such'space, and has a lateral Opening ad.-" jacent its, inlet end, in communication'with the space.

A purposeof sucha system type is.to prevent stratification inthe space served, and the .duct under consideration maybe a riser ductahaving. upward. flow therein, as.-- servedby .a. .furnace lo,- cated in a .basementjor, it maybe adowndraft. duct, as served bya furnace. located in the attic.

If'the duct be ariser: .duct," its outlet opening is located adjacent the ceiling of the space. and with its lateral opening"substantiaily"therebelow and adjacent the floor or baseboard of the space. on the other hand where'the 'duct"-is"employed with down'draft, itsoutletend is arranged to'dischargeinto the'spaceadjacentthe floor thereof and its lateralopeningis substantially thereabove,

adjacent the ceiling of the space.

In"either"event stratifioation'within the space is avoided" since,-

as will i hereinafter appear, air fiow is induced from the space into the duct-byway of the-' la'teral opening, 'by flow through the duct of'the hot air *enteringits inlet -end "under pressure; which warm airentrainsthe-zair from" the. space atone eleyation'and returns the same to -the space" at' another elevation," thereby =preventing*stratificationuvithin the space.

Thus, :iftherduct be a riser it isprovidedwith' meanswhereby inioperationrair is caused to recir cu'late inithespace, .Wlth 'fiowinto' the duct byway of its :lower, lateral: openingwithientrainment in 1 1711835111013 airJStream zthereadjacent;commingling with-.nthehot airasritcrises: in;the::duct;"the'mix--.

ture-r: at i: -the:: thereby: modulated-:2; temperature: emerginginto the space- :aetherelevated Zduet. outs;

let.

Both riser and down draft duct arrangement being known to'theart in the general-type of system under consideratiom-andthe inventionherein being equally applicable to both .arrangementaior. conveniencein terminology, a riserhduct arrange,- ment will 'bespecifically referredto hereinafter in .thespecifi'c'ation andfclaim; butit is tosbe appreciated that. the same parts,"in upside down 311: rangement would cooperate as "well in principal functions were their disposition. ,reversed and therefore upside" down of that specifically dis closed.

A'principal object of this invention is to im 1 era-m.-v (Cl. 98-38) provetheefliciencyof: that sectionof the ductjadj'acent. the lateral bpeningthrough whichtair-is' induced for recirculation'by entrainment, entrain; ment is" accomplished; and preferably control is had as {will hereinafterr'appear; to theends that.

structure :issimplified, and. maximum induction and thereby recirculation 'had,together,with mini. mumrestrictionof 'flow'of the "forced hot air.

Further objects and advantages will be appar.-' ent from the following description, together with the accompanying drawing which is;a somewhat conventionalized View of a pertinent section of a riser duct in vertical'disposition as employed'in use, generally in typical sectional el'vationasto entrainment parts. and in elevation as. .toP. priIi.-.-5 cip'al control parts...,

With reference now to. .the .drawing, A irepre-.-. sents generally the portion of,.the..riser .du'ct 'un-=. der consideration, rectangulariin' .transversemsection, with a irontlwalliil .and rearwallL'ziinter connected bya pair.of"sidelwallsl3.-- Astisrusual in'the art, thettransverse..dimensionof thefront and back .walls may ,be several.timesfithatroflthe sidewallst," so that the risermay be located iWithra in. one of the. wallsof .lthe room orwoth'er buildingspace to be served.

The section under consideratiommay be--.pro,-:-

vided at itsaupperv andiower .extremities. with means .for connection torother units-to-z-form the riser, so that this particularsection may; be..-.con-: veniently. manufactured and shipped as'a runitaori the parts under consideration may be otherwise incorporated. in thelriser duct to form a part-there-- Accordingto this invention the: section OI -Uhlba is provided-with a rectangular :lateralopeningn 4 in. its front .wall I ,which :opening; preferablyand: as. mere indicated isf-'p rovided.-.- withframed -grille nsane 5, both substantially of full width.

A curvedgpartition:.16 r-is: arranged-:"betweenrzthe side walls-.3 to extend from-the lowerzextremity of the opening 4 -rearwardly eand upwardly "5130- a of the'duct;

Whathas thus'iar been described includes: the entrainment portion-:of' .this' sinvention; by? which: recirculation in "the 98133106 served is had iii-the following manner.-

The. riser section .is installed within :or-preferablyv adjacent. a wallof;the space .8 to be 'heated,- so :that. its ;.opening .4 -=-is-.-in,.oommunication with.

such space at a low elevation therein, and the riser portions not illustrated extend above those portions illustrated, to an outlet into said space adjacent the ceiling thereof, and preferably facing the same direction as the opening 4, as is usual in the art.

Forced hot air at substantial pressure and high temperature is supplied to the lower extremity of the riser, as indicated at C, as by a suitable connection from a central furnace. The nozzle 7 formed by the partition 6 increases the velocity of the hot air stream and produces an upward jet D from the nozzle mouth, as indicated by the broken line E. This jet is adjacent the back wall 2 of the duct, extends entirely crosswise between the side walls 3 of the duct and flows divergently from the nozzle toward the front wall I of the duct, not meeting such front wall, however, until it is at a very substantial elevation above the opening 4.

The front face of the jet thus has a very great area all of which is exposed to a corresponding area of air in communication with spac B. by way of the opening 4. This great area of contact between the two sources of air, is effective for equally great entrainment of the space air by and in the hot air of the nozzle jet, thereby inducing a correspondingly great flow of air from the space E by way of the opening 4, as indicated by the arrows F, the opening 4 being at a low elevation in the space served, the induced stream F is at a low temperature. As it commingles with the jet D of hot air, equalization in temperature is had, so that the temperature of the composite stream which emerges from the top of the riser duct into the space served, is at a lower temperature than the hot air by which the riser duct is served, but at a substantially higher temperature than that at which'air enters the duct by way of the opening 4.

Also, the velocity of the composite stream is very substantially lower than that prevailing at the mouth of the nozzle I. Thus, as will be apparent by one familiar with the art, temperature differential between floor and ceiling in the space to be heated is greatly reduced by the recirculation, yet the velocity of heating air within the space does not exceed reasonable limits, although the velocity of the forced warm air supplied to the riser duct may be very substantial.

It will be noted that by the arrangement described, heat exchange between the hot air and recirculating air streams takes place commencing at the upstream or lower extremity of the partition so that corresponding tendency to uniform temperature of the composite stream emerging into the space served, is enhanced.

Also, it is to be noted that the disposition of the partition 6 is such as to reject any solids or liquids which might find their way through the grille 5.

The invention also includes means for controlling the fiow through th riser duct.

Such means includes a damper 8, located below the partition and consequently streamwise ahead of the nozzle 1, and hinged to the back wall 2 of the duct section as at 9. The damper extends substantially between the side walls 3 but with sufficient clearance therefrom to permit adjustment on its hinge 9 between full open position against the back wall 2 and full closed position against the front wall I, as indicated by the broken swing line [6.

For control of the damper 8, a member H3 is mounted in any convenient manner as by slot H in the face of the grille 5 to be vertically 4 adjusted thereon, and securable in adjusted positions, as by a hand nut II. The member HI extends within the curve of the partition 6 and carries a member 12 secured, as at l3, to the damper 8. The member [2 extends through a slot or other opening 14 provided for its clearance in the partition 5. Ashere indicated, the member l2 has rigid connection with the member l0, hinged connection at 13 with the damper 8, but in itself has sufficient flexibility to accommodate the angularity produced at its lower end by the swing of the damper; spring wire being satisfactory for the purpose.

"tween full on or off positions.

Permitted adjustment of the member may be sumcient that the damper B be adjustable be- Or the damper may also be employed in initial balancing of the system'by provision of a stop, conventionally indicated by the screw [5 to limitthe adjustment in damper-opening direction.

By the damper arrangement disclosed, the damper has compact relation to the partition 6 and might in fact be located much closer to the partition than as here illustrated.

Also, in any adjusted position of the damper, full wipe of the hot air stream against the partition 6 is bad, with consequent heat exchange through the partition, as above described.

As hereinabove stated, while a riser duct arrangement has been specifically illustrated and described, and for convenience terminology consistent therewith employed in the specification and following claim, neither the invention nor the claim are to be considered as limited in scope thereby; since the invention would be equally applicable in a duct arranged for down draft operation, simply by disposition of the parts upside down as will be apparent.

I claim:

A device of the class described,'for use in a forced air heating system by employment in a riser duct thereof substantially below the duct outlet, to provide controlled recirculation of air in the space served by said duct, said device comprising: a .duct section having, when disposed as to be used, its bottom open to receive hot air under pressure, its top open for connection in said riser duct for delivery to said outlet thereof, a front opening for communication with said space, a partition extending from the lower extremity of said front opening inwardly and upwardly to a location adjacent the rear wall of said section, to there provide a laterally extending nozzle for entrainment in the stream therefrom, of air'induced thereby from said space by way of said front opening, said duct section having a damper hinged to said rear wall for swing ing adjustment therefrom to positions below said partition, to limit' flow of hot air to said nozzle and to cause permitted flow to wipe saidpar tition, and means for adjusting said damper by way of said front opening.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,296,968 Klein Mar. 11, 1919 1,832,638 Kitchen Nov. 17, 1931 1,878,012 Stacey, Jr et al. Sept. 20, 1932 2,345,537 Keep Mar. 28, 194% 2,348,127 Grimes May 2, 1944 2,406,643 Spieth Aug. 2'7, 1946 2,429,619 Hamblin Oct. 28, 194!- 2,6l3,587 MaoCracken. Got. 14, 1952- 

